This invention relates to an information system for providing a part of a plurality of computer resources and the function thereof to a plurality of business systems of customers, or in particular to a management technique of an information system adapted to meet sharp changes of the processing request of each business system.
An information system finds practical applications in which a part of a plurality of computer resources and the function thereof are provided to on-demand service providers and data centers mainly dealing with the batch processing or customers who are required to handle/process a predetermined amount of accesses and data processing jobs within a predetermined period of time.
The importance of constructing a business system using this information system and reducing the cost by improving the business efficiency has been widely recognized, and demand for this information system has been ever on the increase. In the operation of an information system such as the internet Web site publicly accessible from a multiplicity of unspecified customers, for example, the computer resources capable of processing a predicted maximum load (accesses or processing requests) are always assigned.
The information system, therefore, normally holds excessive computer resources for a light load, and poses the problem of how effectively the computer resources are to be utilized.
US 2004/0054780A1 proposes a technique in which host resources that can be shared by a plurality of business systems are prepared with the intention of overcoming an unexpectedly heavy load without any host resources capable of handling the maximum load estimated for each business system. In this case, a host is retrieved from a server pool and a disk image (a software group sufficient to make the host resources “active”) prepared to be built in the business system is copied to the host.
The related copying technique is disclosed in JP-A-2003-316581, for example, in which the copying efficiency is improved by comparing a list of software already installed in the host with a list of software to be installed in the host, and installing only the difference for a plurality of computer resources.
Also, US 2005/0102674 briefly describes a method, in which standby computer resources in dead standby mode are loaded into active computer resources by predicting a load based on the past operation history, and thus the logical server transfer (provisioning) is achieved.
An information system is known in which standby computers are made available in the case where the processing requests are concentrated on a given business system. In the information system operating the Web site, for example, the process is executed to assign the accesses of the processing requests to the computer resources in the server pool where a plurality of servers stand by. Also, standby computer resources in dead standby state are newly added to the server pool to meet the processing requests.
In the prior art, the entire disk image (software) of the computers in operation are copied to the standby computers to be made available, and therefore the preparation time consumes too much time. Specifically, in copying the disk image of the computer in operation (active host) of a business system, the time required for preparation is increased in proportion to the image capacity, and therefore, it is difficult to handle an unexpectedly sharp load change readily.
Also, the conventional methods fail to make specifically apparent how to quickly find out a server assigned to a business system from a plurality of servers (standby computer resources) in a server pool, and what kind of software environment construction means is used for the server to assure the quickest assignment to the business system. Thus, it is not clear how an information system is to be constructed.